Six-address scheme for multiple hop forwarding in wireless mesh networks

ABSTRACT

A six field address scheme identifies both the originating point and the endpoint of a data frame enabling multiple hop forwarding through a plurality of intermediate mesh points in a wireless mesh network. Data frames originating or ending at a point outside of the wireless mesh network access the wireless network at a mesh access point using a legacy address scheme. The legacy address schemes are converted to a six address scheme using a proxy address table at the access point. Each mesh access point includes not only a routing table but a proxy address table as well as enabling the mesh access point, and/or mesh portal points, to convert address schemes having less than six address fields to the six field format. Subsequent to the conversion, mesh points within the wireless mesh network need only the routing table to facilitate the forwarding of the data frame.

RELATED APPLICATION

The present invention is a continuation-in-part of U.S. patentapplication Ser. No. 11/771,937 filed, Jun. 29, 2007 entitled,“Six-Address Scheme for Multiple Hop Forwarding in Wireless MeshNetworks,” The present application further relates to and claims thebenefit of priority to U.S. Provisional Patent Application No.60/972,145 filed Sep. 13, 2007, which is hereby incorporated byreference in its entirety for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention relate, in general, to forwardingdata frames in a wireless network and particularly to a six fieldaddress scheme for multiple hop forwarding of data frames in a wirelessmesh network.

2. Relevant Background

An increasing number of people today depend on the ability to connect towireless networks in a variety of situations. While one-hop accesspoints were a suitable solution in the beginning, they suffer fromproblems such as low coverage area and being overloaded. One solution tothis dilemma is the use of wireless mesh networks (“WMN”).

Mesh networking is a way to route data, voice, video, and instructionsbetween the nodes of the network. It allows for continuous connectionsand reconfiguration around broken or blocked paths by “hopping” fromnode to node until the destination is reached. Mesh networks differ fromother networks in that the component parts can all connect to each othervia multiple hops, and they generally are not mobile. Thus each node ina mesh network can communicate with other nodes in its immediateneighborhood.

Whereas the Internet is mostly a wire-based, co-operative electroniccommunication infrastructure similar to the international postalagreement, in that messages are mutually delivered and relayed withintheir separate domains free of charge (i.e. if you relay my messageswithin your domain I'll relay your messages within mine), a mesh is awireless co-operative communication infrastructure between a massiveamount of individual wireless transceivers (i.e. a wireless mesh) thathave Ethernet-type capabilities.

This type of infrastructure is decentralized (with no central server)providing a relatively inexpensive, very reliable, and resilient systemas each node need only transmit as far as the next node. Nodes act asrepeaters to transmit data from nearby nodes to peers that wouldotherwise be too far away to reach, resulting in a network that can spanlarge distances without wired cable in between, especially over rough ordifficult terrain. Mesh networks are also extremely reliable, as eachnode is connected to several other nodes. When one node drops out of thenetwork, due to hardware failure or any other reason, its neighborssimply find another route. Extra capacity can be installed by simplyadding more nodes. The network solutions involving mesh networks are asdiverse as communications in difficult environments such as homenetworks, office networks, public access networks, emergency situations,tunnels and oil rigs to battlefield surveillance and high speed mobilevideo applications on board public transport or real time racing cartelemetry.

Mesh networking operates on a principle similar to the way packetstravel around the wired Internet—data will hop from one device toanother until it reaches a given destination. Dynamic routingcapabilities included in each device within the network allow this tohappen. To implement such dynamic routing capabilities, each deviceneeds to communicate its routing information to every device it connectswith, “almost in real time”. Each device then determines what to do withthe data it receives—either pass it on to the next device or keep it.Obviously each node within the network must have a unique identitycalled a network address to facilitate peer-to-peer communication amongthe nodes. Due to the irregular and spontaneous nature of IP meshnetwork topology the address assignment becomes a non-trivial issue. Toaddress this issue each mesh point in a 802.11 mesh networks use a mediaaccess control (“MAC’) address allocated by the manufacture of thedevice.

The Institute of Electrical and Electronic Engineers (“IEEE”) 802.11standard identifies services that must be provided by a distributionsystem. A distribution system, be it wireless or wired, is thefundamental part of a network as it is the mechanism by which one accesspoint communicates with another to exchange frames, forward frames tofollow mobile stations from one location to another, and to exchangeframes with wired networks.

To better understand the present invention, consider a typical wirelessnetwork as is known in the prior art and shown in FIG. 1. In thissimplified depiction of a wireless network 100, the external network 110is coupled to a gateway or portal 120 via a wired infrastructure 115.The portal 120 may be an Ethernet bridge and not only serve the role asa portal to the external network 110 but also as an access point for thewireless network 100. This simplified example of a wireless network 100is a typical Basic Service Set (“BSS”) in 802.11 networks. In such awireless network several stations are associated with an access point orportal. The access point connects the wireless network with a wirednetwork and normally relays frames among the stations with which it isassociated. In this example, the network 100 includes three nodes, alaptop 130, a desktop 140 and a printer 150. Normally, each communicateswirelessly with portal 120 via a single hop in the network. Thus, when aprint command is generated from either the laptop 130 or the desktop140, it normally travels to the printer 150 via the portal/router 120.

FIG. 2 is a depiction of a multiple-hop distribution system (“DS”) 200(mesh network) as is known in the prior art. The DS 200 shown iscomprised of three nodes or mesh points (“MPs”) 220, 230, 240, 250, 260.In a mesh network, a mesh point is a computer with a network interfacecard (“NIC”) or a handheld computer or similar device with access to thenetwork. The uppermost MP 220 is in this depiction coupled to anexternal network 110 via a wired infrastructure 115. This uppermost MP220 also serves as a mesh point portal (“MPP”) for the remaining MPs230, 240. MPs 220, 230 and 240 in the DS 200 are coupled to each othervia a single hop. Two MPs 230, 240 shown in FIG. 1 are each coupled to amesh access point (“MAP”) 250, 260. The two MAPs 250, 260 are eachconnected to two stations (“STA”) 270, 280 forming two respective BasicService Sets (“BSSs”) 275, 285. Generally, any entity that has stationfunctionality and provides access to the distribution services via thewireless medium for associated stations (“STAs”) is an access point.MAPs are part of a mesh network as they are an independent MP withaccess point functionality. Therefore, each MAP has routingfunctionality. One skilled in the art will recognize that the 4-addressformat of 802.11, with the help of default routing to the root of thewireless mesh network (wherein the root possesses a global proxy table)plus a local proxy table in each MP (outside of the root), can supportframe forwarding in a multiple-hop mesh network.

As previously mentioned, each node or MP must have a unique networkaddress and there must be a means by which to direct frames of data tothe correct address. Based on a distribution system shown in FIG. 2, anaddress scheme was developed having four (4) fields. This four addressformat enables implementation of relay-type services in a multiple-hopwireless DS with the help of default routing to the root (having aglobal/local proxy table at the root and/or global/local proxy table ineach MP). The root has a global proxy table for all STAs associated withMAPs (to map STAs to MAPs that they associate with) and all externalnodes of MPPs (to map external nodes to MPPs). Each MP has local proxytable for all STAs associated with MAPs that are part of its subtree andall external nodes of MPPs which are part of its subtree. Each MAP has alocal proxy table for all STAs associated with it to decide whether thereceived frames are from a STA with which it is associated.

In the four address format, the source address (“SA”) and destinationaddress (“DA”) can be different from the receiver address (“RA”) andtransmitter address (“TA”). In the previous example each MP and STApossess a unique address and the root (MPP) maintains a global mappingtable for all of the STAs associated with MAPs registered in the meshnetwork. This mapping table maps each STA to its associated MAP. It alsomaps each external node to a MPP which can forward frames to it. Intree-based routing, the root also maintains a routing table for each MPin the mesh network. Each MP maintains a routing table for its child MPin its subtree. It also maintains a local proxy table for all STAsassociated with MAPs which are part of its subtree and all externalnodes of MPPs which are part of its subtree. In link-state routing whichis not shown here, each MP maintains a routing table for each MP in themesh network. It also maintains a global proxy table for all STAsassociated with each MAP in the mesh network and all external nodes ofeach MPP in the mesh network. Each MP tries to find the next hop to thedestination MP/proxy MP through its routing table. If the destinationnode is an external node of the mesh network, the proxy table is used tofind the destination proxy MP of the destination external node. If a MPcan not find route for these frames, the default route is used. Thisdefault route takes all frames to the root. At the root the next hop tothe destination can always be determined since the root has the pathinformation to all the MPs in the mesh network and each MAP is aware ofany STA affiliated with that access point. We can easily find that proxytables are maintained in each MP but this approach requires substantialallocation of memory and is difficult to maintain. Also the defaultrouting will be used in the path to root which is not good.

FIG. 3 shows a four block addressing scheme for a frame of data underthe 802.11 standard as is known in the prior art for transmitting framesfrom one wireless station to another wireless station traveling throughthe root. The address scheme 300 comprises four address blocks. Addressblock number one 310 identifies the receiver address and address blocktwo 320 identifies the transmitter address of the data frames. Blocksthree 330 and four 340 represent the different meaning of the dataframes respectively when the data frames are transmitted from a STA toits associated AP, from its associated AP to a STA and in distributionnetworks. Blocks three 330 is the destination address and block four 340is not applicable when the data frames are transmitted from a STA to itsassociated AP. Blocks three 330 is the source address and block four 340is not applicable when the data frames are transmitted from itsassociated AP to a STA. Blocks three 330 is the destination address andblock four 340 is the source address when the data frames aretransmitted in distribution networks. Thus, in the example of a framebeing sent from STA1 270 to STA2 280 via the root (MPP) 220, the finaldestination is STA2 280 and the originating station is STA1 270.

Initially the immediate transmitter of the packet is STA1 270 and thereceiver is MAP 1 250. Thus, the first iteration of the address schemeis as shown in block 350. Note that address block four is omitted. TheSTA to MAP connection is not part of the wireless distribution systemthus the forth address in not applicable. After MAP1 250 receives theframe, it tries to find the destination STA2 in its BSS 285 or therouting table. Because MAP1 can not find STA2 in its BSS and the exactpath for STA2, the default path to the root is used and the next hop tothe root is MP1 which is the receiver address (RA). The addresses ofblock one 310 and block two 320 change from MAP1 and STA1 to MP1 andMAP1, respectively. Note that the destination address and source addressin block three 330 and block four 340, respectively, reflect theultimate destination and the original source. The address scheme is asshown in block 360. When MP1 230 receives frames for STA2 from MAP1, itdoes the same process as was done by MAP1 (see block 370) and finds thatthe next hop to the root is the root. Thus the MP1's read of thedestination address STA2 is unrecognized causing the frame to be routedto the portal or root of the DS 200. When the root receives frames forSTA2 from MP1, it finds the proxy MP of STA2 which is MAP2. Then theroot finds the next hop of MAP2 which is MP2. The addresses of block one310 and block two 320 thereafter change to MP2 and root, respectively(block 380). Again note that the destination address and source addressin block three 330 and block four 340, respectively, reflect theultimate destination and the original source. When MP2 receives framesfor STA2 from the root, it finds the proxy MP of STA2 that is MAP2(block 385). MP2 then finds the next hop of MAP2 which is MAP2. Theaddresses of block one 310 and block two 320 change to MAP2 and MP2,respectively. (Again the destination address and source address in blockthree 330 and block four 340, respectively, reflect the ultimatedestination and the original source.) When MAP2 receives frames for STA2from MP2, it finds that STA2 is one of its associated STA. Then MAP2uses the address scheme from DS to STA. The addresses of block one 310and block two 320 change to STA2 and MAP2, respectively. Finally, notethat block three 330 is the original source address and block four 340is omitted (block 390).

Significantly, the previous examples contemplate one possible method ofmultiple hop frame forwarding via 802.11 four address format, possessinga proxy address list in each MP and default routing. However, this fouraddress scheme cannot efficiently support all cases of routing andforwarding in multi-hopping mesh networks, in other words, defaultrouting must be used in the path from the source to the root if thesource can not find a path for the destination in the routing table.Furthermore, traffic grooming (“TG”) mesh networks, wherein frames fromone STA associated with a MAP are delivered through multiple MPs toanother STA associated with another MAP, is not efficiently supported,in other words, default routing and proxy table in each MP must be used.

SUMMARY OF THE INVENTION

Briefly stated, embodiments of the present invention involve an addressscheme for multiple hop forwarding of data frames in a wireless meshnetwork. According to one exemplary embodiment of the present invention,a six field address scheme is used to identify both the originatingpoint and the endpoint of a data frame and to enable multiple hopforwarding of the data frame through a plurality of intermediate MPs ina wireless mesh network. In one embodiment of the present invention, thedata frame either originates or ends at a point outside of the wirelessmesh network. The data frame accesses the wireless mesh network at a MAPor a MPP and subsequently travels through the wireless mesh networkusing the six field address scheme and routing tables found at each MP.

Legacy address schemes used to transport the data frame to and from thewireless mesh network at the mesh network interface are converted to thesix address scheme using a proxy address table. In one embodiment of thepresent invention, this interface takes place at a MAP. Each MAPincludes not only a routing table but a proxy address table as well. Theproxy address table enables the MAP, and in other embodiments MPPs, toconvert address schemes having less than six address fields to the sixfields format. The proxy table enables the root to find the proxydestination MP. Subsequent to the conversion, MPs within the wirelessmesh network need only the routing table which includes MPs as therouting destinations to facilitate the forwarding of the data frame. MPsoutside of the root, MAPs and MPPs are not required to maintain a proxyaddress list for the entire network.

In another embodiment of the present invention, methods for multiple hopforwarding data frames throughout a wireless mesh network are described.According to one method, a data frame originating at either a MP withinthe network or a STA outside of the wireless mesh network is associatedwith a six field address scheme. Those data frames that originate at aMP within the wireless mesh network are associated with the six fieldaddress scheme upon creation. According to one embodiment of the presentinvention, one of the six address fields is associated each with theorigination or beginning point of the data frame and the destination orendpoint of the data frame.

Those data frames that originate (or are destined) outside of thewireless mesh network and are associated with legacy addressing schemespossessing less than six address fields, are converted to the six fieldaddress scheme of the present invention upon interfacing with thewireless mesh network. In one embodiment a legacy station outside of thewireless mesh network originates a data frame to be forwarded throughthe network. The station interfaces with the wireless mesh network via aMAP. At the MAP, the legacy address scheme is converted to the sixaddress scheme using a proxy address table for the wireless meshnetwork. When one of the address schemes has been converted, the dataframe is forwarded through the wireless mesh network via multiple hopsand through multiple MPs. Significantly, the data frame is forwarded ateach intermediate MP using only information contained within the sixfield address scheme and a routing table found at each MP. A proxyaddress table is not required at each intermediate MP.

Should the destination of the data frame be outside of the wireless meshnetwork, the six address scheme is converted to the appropriate legacyformat at the interface between the legacy device/station and thewireless mesh network.

In another embodiment of the present invention the data frame arrives toor departs from the wireless mesh network via a MPP. A MPP interfacesthe wireless mesh network with a wired network such as the 802 network.Using a proxy address table, addressing schemes outside of the six fieldscheme of the present invention are converted to the six field addressscheme using a proxy address table. In another embodiment of the presentinvention, a data frame may exit the wireless mesh network via a MPP,travel via a wired network, and return to the wireless mesh network viaa different MPP so as to arrive at the destination in the most efficientand resource effective manner.

In another embodiment of the present invention, information regardingthe source of the data is preserved by modifying fields within the sixfield scheme or by reformatting the six field scheme to a four fieldscheme. When the data frame passes through a root mesh point within theWMN an inquiry is made to determine whether the address found in fieldthree of the six field scheme matches the current mesh points MACaddress. In such a situation the MP checks the address extension mode todetermine whether it possesses a 10 or 11 value. When the addressextension mode is either 10 or 11 a further inquiry is made with respectto that endpoint address found in field five of the six field scheme.When field five includes an address of a mesh point acting as a proxyfor a non-mesh entity, the six field scheme is maintained but fieldsone, two and three are modified to preserve the source information. Whenfield five includes an address of a mesh point within the WMN, a furtherinquiry to the values found in field six and four occurs. When theaddresses found in field four and six match, the six field scheme isreformatted to a four field scheme and value of field one, two and threeare modified to preserve the source information. When the addressesfound in field four and six differ, the six field scheme is maintainedand fields one, two and three are once again modified to preserve thesource information. By following these modifications and reformattingsteps, source information, critical for checking the frame sequencenumber in order to identify and discard duplicates as well as theability to sequence reordering frames, is maintained.

The features and advantages described in this disclosure and in thefollowing detailed description are not all-inclusive, and particularly,many additional features and advantages will be apparent to one ofordinary skill in the relevant art in view of the drawings,specification, and claims hereof. Moreover, it should be noted that thelanguage used in the specification has been principally selected forreadability and instructional purposes and may not have been selected todelineate or circumscribe the inventive subject matter; resort to theclaims being necessary to determine such inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The aforementioned and other features and objects of the presentinvention and the manner of attaining them will become more apparent andthe invention itself will be best understood by reference to thefollowing description of a preferred embodiment taken in conjunctionwith the accompanying drawings, wherein:

FIG. 1 shows a wireless networked computer environment as is known inthe prior art;

FIG. 2 shows a wireless mesh networked computer environment utilizing afour address scheme, proxy table and default routing as is known in theprior art;

FIG. 3 is a four address scheme for the transfer of frames in a wirelessdistribution system for use with a proxy table and default routing as isknown in the prior art;

FIG. 4 shows one embodiment of a six address scheme for wireless meshdistribution systems according to the present invention showing anexpansion of the mesh header possessing address field five and addressfield six;

FIG. 5 is a linear representation of frame transfer in a mesh networkdistinguishing a MP to mesh point link, a mesh path and one embodimentof an 802 communication according to the present invention;

FIG. 6 depicts one example of a mesh networked, wireless distributionsystem, computer environment utilizing one embodiment of the presentinvention to direct frames from one destination to another as well ascommunicating to a STA located outside of the mesh network;

FIG. 7 is an expanded version of the wireless mesh network of FIG. 6identifying multiple MPPs by which to forward a frame utilizing oneembodiment of the six address scheme of the present invention;

FIG. 8 is a tabular representation of a six field address scheme formultiple hop forwarding of a frame within in a wireless mesh networkaccording to one embodiment of the present invention;

FIG. 9 is a tabular representation of a six field address scheme formultiple hop forwarding of a frame from a point within a wireless meshnetwork to a STA outside of the mesh network according to one embodimentof the present invention;

FIG. 10 is an expanded version of the wireless mesh network of FIGS. 6and 7 in which, according to one embodiment of the present invention,frames are directed from one destination to another and wherein a meshpoint is also the destination;

FIG. 11 is a tabular representation of a six field address scheme formultiple hop forwarding of a frame within a wireless mesh network inwhich the address scheme is changed at the root and source data is lost,according to one embodiment of the present invention;

FIG. 12 is a flowchart of one method embodiment forintermediate/destination MP forwarding according to the presentinvention;

FIG. 13 is a tabular representation of a six field address scheme formultiple hop forwarding of a frame within a wireless mesh network inwhich the root uses a four address scheme without loss of source dataaccording to the present invention; and

FIG. 14 is a tabular representation of a six field address scheme formultiple hop forwarding of a frame within a wireless mesh network inwhich the root uses a six address scheme without loss of source dataaccording to the present invention.

The Figures depict embodiments of the present invention for purposes ofillustration only. One skilled in the art will readily recognize fromthe following discussion that alternative embodiments of the structuresand methods illustrated herein may be employed without departing fromthe principles of the invention described herein

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Specific embodiments of the present invention are hereafter described indetail with reference to the accompanying figures. Like elements in thevarious figures are identified by like reference numerals forconsistency. Although the invention has been described and illustratedwith a certain degree of particularity, it is understood that thepresent disclosure has been made only by way of example, and thatnumerous changes in the combination and arrangement of parts can beresorted to by those skilled in the art without departing from thespirit and scope of the invention.

A six address scheme for multiple hop forwarding in wireless meshnetworks is presented herein. According to one embodiment of the presentinvention, a six address scheme is used to direct frames of data fromone location within a mesh network to another location within the meshnetwork via multiple hops without additional resource requirements beingplaced on nodes within the network to maintain a proxy address list orforce the frame to be routed through a root directory. The significanceof the present invention can be appreciated when considering the rapidinterest in wireless computing and communication in the workplace or ateducational institutions. In a mesh having multiple nodes (laptops orother mobile wireless devices) and a limited number of portals to thewired network or infrastructure relative to the number of wirelessnodes, the ability for each wireless node to communicate and pass framesbetween themselves and to associated STAs is of a considerableadvantage. As the number of wireless mesh nodes increase, the number ofpaths upon which a frame can travel increases and thus so doesreliability of the mesh network. Consider, for example, the improvementin wireless communication in a cellular network if rather than each cellphone having to establish and maintain a link with a cellular tower,signal strength or the ability to communicate wirelessly is based onother cellular phones or nodes within a certain range. Those phones canlink to other phones which eventually lead to a portal to the wirednetwork. The present invention enables such an improvement.

FIG. 4 depicts a six address scheme for addressing frames in a wirelessmesh network (distribution system) according to one embodiment of thepresent invention. As shown in FIG. 4, the four address scheme as knownunder the IEEE 802.11 standard is modified by adding an additional meshheader 460. As shown in FIG. 4, a new shim mesh header 460 is addedbetween the current frame format 400 of the medium access control(“MAC”) layer 400 and the logical link logic (“LLC”) layer 405. Withinthe MAC layer 400, four address fields are used to direct the payload410. These address fields include the receiver address (“RA”) 420, thetransmitter address (“TA”) 430, the destination address (“DA”) 440 andthe source address (“SA”) 450.

According to one embodiment of the present invention, a new mesh header460 is added to the frame format existing under 802.11. This new meshheader 460 includes the standard fields 470 typically associated with amesh header such as mesh flags, mesh sequencing, and a durationlimitation (time to live) for the frame as well as two additionaladdress fields 480, 490.

With additional reference to FIG. 5, showing one embodiment of awireless distribution system utilizing a six address scheme according tothe present invention, the usefulness of the additional address fields480, 490 can be understood. The addition of address fields five and sixexpand the otherwise limited 802.11 address scheme. Address fields oneand 2, the RA 420 and the TA 430 represent endpoints of a link between atransmitting location, a first MP 510 and a receiving location, a secondMP 515. Thus, a single hop network can function using just these twofields. In this case the link is the mesh path. Address fields three and4, the DA 440 and the SA 450, represent end points of a mesh pathbetween a destination and a source mesh point including multiple meshpoints 520, 522, 524, 526, 528 or MPPs. In this scenario the combinationof multiple links is the MP.

The addition of address fields five and six expand the address schemefurther by representing endpoints of an end-to-end communication.Communication does not typically terminate at a MP or at a MAP but at aSTA including nodes outside of the wireless distribution system. Thusfields five and six enable the address scheme to efficiently andeffectively direct frames between legacy stations (end points), betweenone or more MPs connected by MPPs 540, MAPs 530, 560, MPs 535, 545, 550,or STAs 570, 580 or any mixture of STAs, MPs, MPPs or MAPs. Here the 802communication is a combination of the MP(s) and the links to the STAs.This communication is enabled by one or more embodiments of the presentinvention. In another embodiment of the present invention two distinctmesh paths being used using address field five and address field 6. Thefirst path is from the source MP to the root MP, and the second path isfrom the root MP to the destination MP. When the frames are forwardingto the root through default path, the root address is put in addressfield 3, so the final destination is in address field 5. When the framesare forwarding to the final destination/destination proxy, the rootaddress is put in address field 4, so the initiating source is inaddress field 6.

FIG. 6 shows one example of a wireless distribution system in a meshednetwork configuration with frame mesh paths facilitated by use of oneembodiment of a six field address scheme according to the presentinvention. As shown in FIG. 6, the external network 110 is coupled via awired infrastructure 115 to a MPP 620. The MPP 620 serves as a gatewayfrom the wireless mesh network 600 to the external network 110.

Within the wireless mesh network 600 exists a plurality of nodes. Thesenodes can include MPs 630, 640, 650, 660, 670, MPPs 620, and/or MAPs680, 690. Each MAP 680, 690 may be associated with one or more STAs 685,687, 695 (legacy stations). A legacy station is a STA that does notpossess the capability of directly participating in a mesh network yetcan access the network via a MAP 680, 690. Also shown in FIG. 6 is a STA4 675 not affiliated with the wireless mesh network 600. While in theFIG. 6 node4 675 is shown as being coupled to the external network 110via a wired interconnect, STA4 can represent another wirelessdistribution system or indeed another wireless mesh network with its ownstations.

The six field address scheme of the present invention enables frames tobe communicated between any of the nodes in a wireless mesh network, oroutside of that network, along multiple paths without using proxy tablesand default routing in internal MPs. FIG. 7 is an expanded depiction ofthe wireless mesh network 600 of FIG. 6. FIG. 7 shows wireless and wiredlinks between the various MPs of the wireless mesh network 600. Forexample, MP1 630 is wirelessly linked to MP2 640. MP2 640 is wirelesslylinked to MPP 620, MP1 630, MP4 660, and MAP1 680. MAP1 680 iswirelessly linked to MP2 640 and linked to STA1 685 and STA2 687 via awired connection.

The movement of frames within a wireless mesh network as shown in FIGS.6 and 7 can generally follow one of three scenarios. Frames can flowfrom one STA to another. For example, a frame originating from STA1 685can be directed toward STA3 695. A frame can also originate from a MPand be directed toward another MP or a STA. For example, a frameorigination at MP1 630 can be directed to MP5 670. Finally, a frame canoriginate from the mesh network and be directed outside the network suchas a frame starting at STA2 687 and ending at STA4 675. In eachscenario, multiple paths are possible.

The present invention fully supports and is compatible with HybridWireless Mesh Protocol (“HWMP”) and Radio Aware—Optimized Link StateRouting (“RA-OLSR”) protocol. With respect to both of these protocols itis important to understand maintenance of STA association information.(Note: external node associations with MPPs in wired networks can betreated the same as wireless STAs) With respect to HWMP (HWMP includeson demand routing part (AODV) and proactive part (tree based routing)),each MAP/MPP locally maintains its STA association and responds to aroute request message when any of the destination addresses match one ofits associated STAs. For HWMP proactive tree-based routing, each MAPregisters its associated STAs with the root and each MPP registers itsassociated external nodes with the root. In time based regulatoryscenarios, the root maintains a global mapping table for all MPs andSTAs in the wireless mesh network according to the registrationinformation. With respect to RA-OLSR each MAP/MPP broadcasts itsassociated STAs to other MAPs/MPPs and each MAP/MPP maintains a globalmap for associating STAs to their associated MAPs. While the presentinvention is fully compatible with these aspects of the RA-OLSR and HWMPconfigurations, it alleviates many of the requirements in bothprotocols.

Fifth address field and sixth address field are used in the followingcase: 1) when the end points of IEEE 802 communication are non-meshnode/STA which communicate over a mesh via proxy MPs; 2) When the endpoint MPs communicating with each other via a root MP in HWMP proactivetree routing mode, where two distinct mesh paths are used (the firstpath from the source to the root MP and the second path being from theroot MP to the destination MP). With HWMP proactive tree routing mode,if the source MP can not find the destination of a frame from itsrouting table or the frame is from one STA associated with it, it putsthe destination and the source to fifth and sixth address field, theroot to third address field, its address to fourth address field. Whenthe root receives a 6-address frame, it tries to find the proxy of thedestination (fifth address) from its proxy table or routing table. Ifthe proxy is found and the root is not the proxy MP, third address fieldis replaced by the proxy address. Otherwise third address field isreplaced by the fifth address field. With RA-OLSR, if the source MPfinds the proxy destination of a frame from its proxy table or the frameis from one STA associated with it, it puts the destination and thesource to fifth and sixth address field. If the source MP finds thedestination of a frame from its proxy table, it puts the proxy MP'saddress to third address field, its address to fourth address field.Otherwise it puts destination address to third address field, itsaddress to fourth address field. Since in six address scheme each MP canalways find next hop for the destination MP/root MP from the routingtable, the addition of a fifth and sixth address field representing theendpoint destination and the endpoint source respectively alleviate eachMP's requirement to maintain a proxy table matching STAs/external nodesto their proxy MPs. While this is not the only solution to multiple hopforwarding in a wireless mesh network, it provides the significantadvantage of minimizing additional resource overhead at each node withinthe network.

To fully understand the operational implementation of a six addressfield scheme consider the following examples of the present invention.Referring again to FIG. 6, one skilled in the art will recognize thatmultiple paths exist between many of the nodes within the wireless meshnetwork 600. In one embodiment of the present invention a frameoriginating at STA1 685 and directed toward STA4 675, outside thewireless mesh network 600, can travel through the wireless mesh network600 via MP2 640, MP4 660, MP3 650, or any combination thereof.Ultimately the frame must arrive at MPP 620 to exit the wireless meshnetwork 600 and travel to node4 675 via, in one embodiment, a 802network.

Likewise a frame originating at MP1 630 and directed to STA3 695 neverneed leave the wireless mesh network 600 yet the path upon which theframe travels is one of several routes. FIG. 7 depicts two possibleroutes for such a movement of a frame of data. In the first route 800the frame passes from MP1 630 to MP2 640 and then proceeds to the root(MPP 620) wherein it is directed to MP3 650, MAP2 690 and ultimatelyarrives at STA3 695. An alternate route 805 also passes through MP2 640but instead of proceeding to the root (MPP 620) the frame is directedthrough MP4 660 and MP3 650 before it arrives at MAP2 690 and thereafterSTA3 695.

The determination of what path to follow rests on several criteria andis determined by routing protocol present and operating at each MP.These include but are not limited to bandwidth of the established linksand the quality of the link between various MPs. According to one aspectof the present invention and with respect to the information carried bythe frame within address field three (address field five may be used tofind the destination MP using a proxy table), any and all availablepaths are equally capable of forwarding the frame to its ultimatedestination. There is no need for the frame to pass through the root(MPP 620) although it may, should that path be the best suited route.Similarly the frame does not require each MP to possess knowledge of theassociation of STA3 695 with MAP2 690. That information is maintainedwithin the frame itself.

FIG. 8 depicts an illustration of the changing aspects of the six fieldsof the address scheme according to one embodiment of the presentinvention as a frame moves from its source to its destination along thefirst path 800 shown in FIG. 7. As the frame originates at MP1 630 thesix fields of the address scheme identify not only that it is beginningits path from MP1 630 but that it is destined for STA3 695.

Before the frame arrives at STA3 695 it will, in this embodiment, passthrough four other nodes of the wireless mesh network. Accordingly theaddress scheme will be modified five times as is reflected in FIG. 8.Fields one 810 and two 820 consistently reflect the receiver address andthe transmitter address for each hop. Field three 830 maps thedestination as the root or the MPP 620. The root thereafter maps theframe to MAP2 690. Accordingly field three 830 indicates the destinationaddress as MPP 620 for the first two hops and then MAP2 690 for the nexttwo. The fourth address field 840 reflects that the frame originatesfrom MP1 630. Significantly, field five 850 and field six 860 remainconsistent throughout. Field five 850 indicates that the end pointdestination is STA3 695 and field six 860 indicates that the end pointsource is MP1 630. The transition between STA3 695 is based on thelegacy address scheme for a frame from an AP to its associated STA. Thusfields four, five and six are not applicable. Field one 810, the RA,indicates STA3 695, field two 820, the TA, indicates MAP2 690, and fieldthree, the source in this particular scheme, indicates MP1 630 asconveyed to it from address field six 860.

Note that during the frames transition through the MPs of the wirelessmesh network 600, address fields five 850 and six 860, remain unchanged.While they convey end point source and destination information, thesefields do not need to be processed with an exception that the root mayfind the proxy MP for the destination. Only data within the first fouraddress fields needed to be dealt with inside the mesh. This greatlysimplifies the forwarding process.

In this example of an application of one embodiment of the presentinvention, a tree-based routing in HWMP from MP1 630 to STA3 695 wasused in which the root, MPP 620 was identified as the default route. Theframe was forced to go through the root to arrive at the destinationsince the on-demand alternative routing path with better link qualityhas not been found. In another embodiment of the present invention theroot is not identified as the default address and the MPP 620 simplyacts as anther MP within the wireless mesh network 600. In yet anotherembodiment of the present invention, link state routing using RA-OLSR isutilized. In such a case each MAP and MPP broadcast is associated STAsto other MAPs and MPPs. Accordingly each MAP and MPP maintains a mappingof the STAs to their associated MAP.

In another exemplary embodiment of the present invention, the sixaddress scheme for multiple hop forwarding in a wireless mesh networkcan pass frames to locations outside of the network. FIG. 6 depicts anode, STA4 675, located outside of the wireless mesh network 600. STA4675 in this figure is a single node that is coupled to the externalnetwork 110 via a wired link. However, STA4 675 could also representanother MPP linking the external network 110 to another wireless meshnetwork having multiple MPs, MAPs and STAs. A path 900 presenting theroute of frame originating from STA1 685 and directed to STA4 675illustrates yet another feature of the present invention.

As the frame originates in STA1 685, as illustrated in FIG. 9, itpossesses information with respect to its destination embedded in theaddress scheme communicated to MAP1 680. The frame originating from STA1685 uses a four address scheme with three fields applicable: addressfield one, address field two and address field 3, since it is a framefrom a STA to its associated AP. Field one 810 identifies MAP1 680 asthe RA and field two 820 identifies STA1 685 as the TA. Field three 830in this protocol identifies the end point destination STA4 675. Usingthe same six field address scheme described with respect to FIG. 8 andpath 800, as the frame arrives at MAP1 680, a six address scheme formultiple hop forwarding of frames is placed into effect. Previous fieldone 810, the RA is mapped to the TA in field two 820. The previous TA infield two 820, STA1 685, is recognized as the end point source and ismapped to field six 860. The previous end point destination residing infield three 830, STA4 675, is mapped into field five 850 of the sixaddress field scheme. The frame passes through multiple MPs as dictatedby link quality, bandwidth and other factors known to one skilled in theart of wireless frame routing. Upon arriving at the MPP 620 the sixfields of the address scheme indicate the RA, TA, DA and SA within thewireless mesh network and the end point destination and the end pointsource. As the frame transitions from the wireless mesh environment tothe external network and ultimately to STA4 675, only two address schemeare required. The end point destination of STA4 675 is mapped to fieldone and, with respect to the wired infrastructure, the originatingpoint, MPP 620, is mapped to field two.

FIG. 10 is an expanded version of the wireless mesh network of FIGS. 6and 7 in which, according to one embodiment of the present invention,frames are directed from one destination to another and wherein a meshpoint is also the destination. FIG. 11 depicts an illustration of thechanging aspects of the six fields of the address scheme according toone embodiment of the present invention as a frame moves from its sourceSTA1 685 to its destination MP3 650 along the path 1005. As the framemoves from STA1 685 to MP3 650 it will travel either via a path thattraverses MPP 620 (the root) or via MP4 660. As previously discussed thedetermination of which path the frame takes is determined in oneembodiment of the present invention by the quality of the servicelocated at each node within the WMN.

Assuming that the frame travels through the root, the address scheme maychange resulting in a loss of source information. FIG. 11 is a tabularrepresentation of a six field address scheme for multiple hop forwardingof the frame within a wireless mesh network along the path shown in FIG.10 in which the address scheme is changed at the root resulting in theloss of source information. In the first iteration of the address schemeas the frame originates from STA1 685 the first field 810 reflects theRA of MAP1 680 and the TA of STA1 685 is found in the second field 820.The third field 830 reflects the destination address in the mesh of MP3650. The fourth field 840 reflects the mesh source which is notapplicable as the source lies outside the mesh. Similarly the fifthaddress field 850 that indicates that the end point destination andsixth address field 860 that identifies the originating point arenon-applicable.

As shown in FIG. 11 and consistent with the six address scheme of thepresent invention, as the frame moves from MAP1 680 to MP2 640 thesecond field of the address 820 is updated to reflect that MAP1 680 isthe transmitting address and MP2 640 is the receiving address. The fifthfield 850 is updated to identify the end point as MP3 650 and the sixthfield 860 is updated to reflect the originating point of STA1 685. Asimilar updating process occurs as the frame moves from MP2 640 to MPP620. Note that the fifth field 850 and the sixth field 860 remainconsistent.

The root MPP 620, however, typically uses four fields to forward theframe. In this case the receiving address field one 810 is updated toreflect MP3 650 and the transmitting address field two 820 is altered toindicate MPP 620. In such a scenario, data regarding the source of theframe is lost. As one skilled in the art will recognize, this scenariois confined to situations in which the address extension mode is equalto 10 and 11.

Within the frame there exists data and a mesh header. The headercomprises, according to one embodiment of the present invention, a MeshFlag, a Mesh TTL, a sequence number, and a Mesh Address Extension. TheMesh Flag includes an address extension mode. The address extension modedifferentiates mesh data and multi-hop action from a four address schemeformat from a six address scheme format. Address extension modes of 10and 11 signify mesh data and multi-hop action utilizing a six addressscheme respectively while an address extension mode of 00 and 01signifies mesh data and multi-hop action using a four address scheme.For example, in a six address scheme of mesh data the third field of theaddress represents the mesh destination address while the fifth addressrepresents the end point. In a four address scheme for mesh data, theaddress extension mode is equal to 00 and the end point is equal to themesh destination address which is found in field three. Field five doesnot exist in the four address scheme.

According to one embodiment of the present invention a comparison ofdestination addresses to that of the current mesh point address isconducted to determine whether a four or six address scheme should beutilized. FIG. 12 is a flowchart of one method embodiment forintermediate/destination MP forwarding according to the presentinvention. In the following description, it will be understood that eachblock of the flowchart illustrations, and combinations of blocks in theflowchart illustrations, can be implemented by computer programinstructions. These computer program instructions may be loaded onto acomputer or other programmable apparatus to produce a machine such thatthe instructions that execute on the computer or other programmableapparatus create means for implementing the functions specified in theflowchart block or blocks. These computer program instructions may alsobe stored in a computer-readable memory that can direct a computer orother programmable apparatus to function in a particular manner suchthat the instructions stored in the computer-readable memory produce anarticle of manufacture including instruction means that implement thefunction specified in the flowchart block or blocks. The computerprogram instructions may also be loaded onto a computer or otherprogrammable apparatus to cause a series of operational steps to beperformed in the computer or on the other programmable apparatus toproduce a computer implemented process such that the instructions thatexecute on the computer or other programmable apparatus provide stepsfor implementing the functions specified in the flowchart block orblocks.

Accordingly, blocks of the flowchart illustrations support combinationsof means for performing the specified functions and combinations ofsteps for performing the specified functions. It will also be understoodthat each block of the flowchart illustrations, and combinations ofblocks in the flowchart illustrations, can be implemented by specialpurpose hardware-based computer systems that perform the specifiedfunctions or steps, or combinations of special purpose hardware andcomputer instructions.

Upon a frame arriving at a mesh point the process begins 1205 withdetermining whether 1210 the address found in field three, signifyingthe destination address, matches the current mesh point's MAC address.If the addresses are different, indicating that the frame has notarrived at the end point, the movement of the frame in the WMN continues1215. When the mesh point address matches that of the destinationaddress a series of questions are raised along with correspondingactions. When such a match occurs the address extension mode field ofthe mesh header is examined 1220 to determine whether the field iseither a 10 or an 11. If the answer is “no” the process continues byallowing the mesh point to process data 1225 and send to an upper layer.

When the response is in the affirmative, the inquiry continues by asking1230 whether the current mesh point is a proxy for a non-mesh pointentity. If the mesh point, being the end point, is a proxy for anon-mesh point entity, the frame is translated 1235 to a formatcorresponding to the non-mesh point entity and queued for transmission.

When the response to the inquiry 1230 is negative meaning that the endpoint is a mesh point within the WMN the system determines 1240 if thecurrent mesh point is a root. If the point is not a root, the mesh pointagain processes 1245 the frame. However, when the mesh point turns outto be a root, one of three courses of action take place.

To determine what course of action is appropriate, the end point addressfound in field five of the six address scheme is compared 1250 to allknown addresses of the WMN. When the address of field five (the endpoint address) corresponds to a known mesh point and the address offield four (the source address) is the same as field six (theoriginating point) the frame is reformatted 1260 to a four address fieldscheme with address field three set to the end point and address fieldfour set to the source address. Thereafter the frame is queued fortransmission.

When the address of field five corresponds to a known mesh point addressand the address found in field four is not the same as the address foundin field 6, i.e. the source, and the origination addresses aredifferent, a six address scheme is maintained 1270 with the followingcaveats. The address of field three (the destination address) is set tothe end point address, field one is set to the next hop on the mesh pathto the destination mesh point, and address field two is set to the rootmesh point address. Once completed the frame is queued for transmission.

Finally, when the end point address found in field five corresponds to anon-mesh point entity that is represented by a mesh point acting as aproxy and known to the root, the mesh point shall update 1280 addressfield three to reflect the address of the proxy, alter field one to bethe next hop mesh point on the mesh path to the proxy mesh point, andchange the address of field two to the root mesh point's address.

FIG. 13 is a tabular representation of a six field address scheme formultiple hop forwarding of a frame within a wireless mesh network inwhich the root uses a four address scheme without loss of source dataaccording to the present invention. Using the previous flow chart andreferring to FIG. 10 it can be seen that upon arriving at MPP 620 withthe next mesh point MP2 650 being the end point, the first scenario ofthe decision tree is invoked. In this case, upon the second hop, thecurrent mesh point would be MPP 620 which is a root. The address offield five 850 corresponds to MP2 640 which is a mesh point within theWMN and known to the root. Similarly the address of field four 840, MP1630, is identical to that of the address found in field six 860,specifically MP1 630. Thus a four address scheme format is used whereinthe address of field three 830 is set to the end point, MP3 650, theaddress of field one is set to the next destination in the hop path, MP3650, and the address of field two 820 is set to the root, MPP 620. Thisfour address scheme format is used since the address of field four 840is the same as field six 860 and no source address information is lost.Stated otherwise, mesh point SA=SA.

In a similar manner FIG. 14 is a tabular representation of a six fieldaddress scheme for multiple hop forwarding of a frame within a wirelessmesh network in which the root uses a six address scheme without loss ofsource data according to the present invention. In this case, the secondoption 1270 is invoked. Again, the current mesh point is MPP 620, theroot, as the frame is on a path to arrive at its end point MP3 650.According to the steps outlined above and with additional reference toFIG. 12, the address of field five 850 is MP3 650, a mesh point withinthe WMN. The address of field four 840, MAP1 680, is not equal to thatof field 6, STA1 685. Thus, the six address format is maintained whereinthe address of field three 830 is set to the end point address of MP3650, the address of field one 810 is set to the next hop in the path MP3650, and the address of field two 820 is set to the root, MPP 620.Again, data regarding the source mesh point is lost.

In a similar fashion the six address scheme can be updated when theaddress of field five corresponds to a non-mesh entity such as STA3 695.The third option 1280 outlined in FIG. 12 is utilized to insure thatonce again mesh point source information is preserved.

The six field addressing scheme for multiple hop forwarding of frames ina wireless mesh network greatly simplifies the forwarding process.Recall that within the wireless mesh network, only fields one throughfour need to be processed. Frames five and six retain the end pointinformation but need not be processed by each intermediate MP. The sixaddress scheme also efficiently supports root-based HWMP proactive treerouting and RA-OLSR. HWMP proactive tree routing which is the defaultrouting protocol in the 802.11 standard. RA-OLSR is an optional routingprotocol in the 802.11 standard. The six field addressing schemeaccording to the present invention, also supports tunneling betweenportal communication.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the present disclosurehas been made only by way of example, and that numerous changes in thecombination and arrangement of parts can be resorted to by those skilledin the art without departing from the spirit and scope of the invention,as hereinafter claimed.

While there have been described above the principles of the presentinvention in conjunction with a six field address scheme, it is to beclearly understood that the foregoing description is made only by way ofexample and not as a limitation to the scope of the invention.Particularly, it is recognized that the teachings of the foregoingdisclosure will suggest other modifications to those persons skilled inthe relevant art. Such modifications may involve other features whichare already known per se and which may be used instead of or in additionto features already described herein. Although claims have beenformulated in this application to particular combinations of features,it should be understood that the scope of the disclosure herein alsoincludes any novel feature or any novel combination of featuresdisclosed either explicitly or implicitly or any generalization ormodification thereof which would be apparent to persons skilled in therelevant art, whether or not such relates to the same invention aspresently claimed in any claim and whether or not it mitigates any orall of the same technical problems as confronted by the presentinvention. The Applicant hereby reserves the right to formulate newclaims to such features and/or combinations of such features during theprosecution of the present application or of any further applicationderived therefrom.

1. In a wireless mesh network having a plurality of mesh points, asystem for delivering a data frame between at least one beginning pointand at least one endpoint, said system comprising a six field addressscheme for facilitating forwarding of said data frame to a mesh pointwithin the wireless mesh network via a path through a plurality ofintermediate mesh points wherein the plurality of intermediate meshpoints includes a root mesh point and wherein said six field addressscheme preserves source information of said data frame.
 2. The system ofclaim 1 wherein preserved source information of said data frame enablesframe sequencing.
 3. The system of claim 1 wherein preserved sourceinformation of said data frame enables duplicate frames to be discarded.4. The system of claim 1 wherein said data frame includes a mesh headerthat includes an address extension mode.
 5. The system of claim 1wherein responsive to the address extension mode being either 10 or 11said six field address scheme is modified to preserve source informationof said data frame.
 6. The system of claim 1 wherein each of theplurality of intermediate mesh points includes a routing table, and therouting table includes each mesh point within the wireless mesh networkand wherein the at least one end points include a plurality of meshpoints communicating with each other via a root in a Hybrid WirelessMesh Protocol proactive routing mode having a first path and a secondpath, the first path being from a source mesh point to the root meshpoint and the second path being from the root mesh point to adestination mesh point.
 7. The system of claim 6 wherein responsive tothe data frame being forwarded through the root mesh point the at leastone endpoint is compared to each mesh point included in the routingtable to ascertain whether the six field address scheme must be modifiedto preserve source information of said data frame.
 8. A method offorwarding a data frame in a wireless mesh network having a plurality ofmesh points using a six field address scheme to an endpoint via a pathwherein at least one mesh point within the path is a root mesh point,said method comprising the steps of: at the root mesh point, determiningwhether a destination address in a field of the six field address schemerepresenting the endpoint of the data frame is a mesh point within thewireless mesh network; responsive to the destination address beingwithin the wireless mesh network, comparing within the six field addressscheme a first address representing a source address field and a secondaddress representing a beginning mesh point address field, andresponsive to the first address matching the second address, modifyingthe six field address scheme to a four field address scheme to preservesource information of said data frame; and responsive to the firstaddress being distinct from the second address, reformatting the sixfield address scheme to preserve source information of said data frame.9. The method of claim 8 wherein each of the plurality of intermediatemesh points within the wireless mesh network includes a routing table,and the routing table includes each mesh point within the wireless meshnetwork.
 10. The method of claim 8 wherein modifying the six fieldaddress scheme to a four field address scheme includes setting, withinthe four field address scheme, a first address field to a subsequentmesh point on the path to the destination address, a second addressfield to the root mesh point, and a third address field to the endpoint.11. The method of claim 8 wherein responsive to the first address beingdistinct from the second address, reformatting the six field addressscheme to preserve source information of said data frame.
 12. The methodof claim 11 wherein reformatting the six field address scheme includessetting, within the six field address scheme, a first address field to asubsequent mesh point on the path to the destination address, a secondaddress field to the root mesh point, and a third address field to theendpoint.
 13. The method of claim 8 further comprising responsive to thedestination address being a proxy address for a non-mesh entity,updating, within the six field address scheme, a first address field toa subsequent mesh point on the path to the proxy address, a secondaddress field to the root mesh point, and a third address field to theproxy address.